The utimate objective of this research project is to develop a routine diagnostic procedure for the detection and quantification of damage to human cardiac tissues. Human heart contains three forms of the enzyme glycerol phosphate dehydrogenase (EC 1.1.1.8; GPDH) which can be separated from each other by an ion exchange chromatography. The major form (GPDH-1) found in heart tissue is either absent or present in very low levels in human liver, skeletal muscle and brain, and GPDH-1 does not react with antibodies which inactivate GPDH-2 and GPDH-3. The three forms will be purified to homogeneity from human heart tissue by a combination of affinity column and classical biochemical procedures. Antibodies will be produced in rabbits against GPDH-1 and will be used to develop a radioimmunoassay (RIA) for the detection of this form in human serum. Similarly, antibodies will be made against GPDH-2 and GPDH-3 and these will be used to investigate the relationships between the three forms as well as to establish individual RIA's. The purified forms will be extensively characterized with respect to biochemical, immunological and biophysical properties. With the above information, double blind tests will be set up for determining the usefulness of the GPDH-1 RIA for detecting and quantitating cardiac infarction.